Balanced pressure pump



4, 1966 F. A. BOWER, JR 3,276,389

BALANCED PRESSURE PUMP Original Filed July 25, 1963 2 Sheets-Sheet 1 INVENTOR. FRANK A BOWER JR.

Oct. 4, 1966 F. A. BOWER, JR

BALANCED PRESSURE PUMP 2 Sheets-Sheet 2 Original Filed July 25, 1963 Y :llllnl v.

INVENTOR FRANK A. BOWER JR.

United States Patent 3,276,389 BALANCED PRESSURE PUMP Frank A. Bower, .Ir., Chicago, Ill., assignor to Panther Pump & Equipment Co., Inc., Chicago, Ill., a corporation of Illinois Continuation of application Ser. No. 297,530, July 25, 1963. This application Aug. 6, 1965, Ser. No. 477,792

21 Claims. (Cl. 103-150) This application is a continuation of my co-pending application SerjNo. 297,530,. filed July 25, 1963, now abandoned.

The present invention relates broadly to fluid operated pressure-balanced diaphragm pumps, and more particularly to a new and improved pump having a polyvinyl fluoride diaphragm which is particularly resistant to abrasion and corrosion by liquids such as paint, paint solvents and other more abrasive materials. This invention is related to that of Paul Schlosser disclosed in patent Ser. No. 235,297, now Patent No. 3,207,080.

Various types of pumps, including diaphragm pumps, have been designed and used for pumping paint and other viscous, or corrosive, or abrasive liquids, but the cost of such devices has been relatively high, particularly in the case of the diaphragm operated pumps, thereby limiting their use to very special situations wherein other types of pumps are not applicable. Because, however, of the particular advantage of a diaphragm pump when used in the pumping of viscous and abrasive liquids, it would be desirable to provide a diaphragm pump which can be of simple construction and compact in design so as to appreciably reduce the cost of manufacturing and maintenance of such apparatus.

When pumping corrosive and/ or abrasive liquids and slurries at high pressures, it has been found that pumps of structure known prior to the above-mentioned application have employed relatively thick, and hence less flexible diaphragms. The efiiciency of such prior pumps was reduced accordingly, and the time required for diaphragm replacement has proven excessive and uneconomical. In addition, when a thick diaphragm failed, there have been occasions when the failure progressed slowly from a small leak to a large leak through the diaphragm be tween the chambers. Both the driving and the driven liquids have become contaminated before the pump ceased to impel and expel the driven fluid. Destruction of parts of the pump, and the prime mover therefor, can result when certain corrosive or abrasive liquids are ingested thereby.

The above-mentioned Schlosser application discloses a balanced pressure pump having a very thin walled flexible diaphragm of good heat conducting material such, for example, as rubber. These diaphragms have proven to be extremely resistant to failure of the character mentioned above. In addition, such pumps operate successfully and economically for pumping materials at very high pressures.

The balanced pressure diaphragm pump to be described more fully hereinbelow is characterized by a diaphragm fabricated from polyvinyl fluoride film, or the like. The thickness of the film may vary between one-half of a thousandth of an inch to thirty thousandths of an inch thick, for example. Such diaphragm can operate between vacuum pressures and ultra-high pressures, limited only by the strength of parts cooperable therewith for securing same and containing the driving and driven fluids. The most useful thickness of the film is determined by the class of finish of attachment parts therefor. For convenience, and not in a limiting sense, a diaphragm made of two-thousandths of an inch thick film has been employed with lathe faced flanged domes forming pumping chambers and through-bolt secured for 3,27 6,389 Patented Oct. 4, 1966 retaining the diaphragm, and other securing parts associated therewith.

Accordingly, a broad object of the invention is to provide a balanced pressure pump having an improved diaphragm structure.

An object of the invention in keeping with the preceding object is to provide a very thin diaphragm which has qualities of corrosion and abrasion resistance.

A further object of the invention in keeping with the above objects is to provide a polyvinyl fluoride film diaphragm for a pump, or the like.

Another object in keeping with the preceding object is to provide a suitably preformed diaphragm.

Another object of the invention is to provide a polyvinyl fluoride film diaphragm with fastening means for securing the diaphragm to other pump parts.

A further object of the invention is to provide a pair of diaphragms, at least one of which comprises a polyvinyl fiuoride sheet.

Further objects and advantages and a better understanding of the present invention may be had by reference to the following detailed specification and claims read in connection with the accompanying drawings, in which:

FIG. 1 is a plan view of a double-acting diaphragm pump embodying certain features of the present invention;

FIG. 2 is a side elevational view of the pump of FIG. 1;

FIG. 3 is a vertical cross-sectional view of a portion of the pump of FIG. 1 taken along the line 33 thereof showing the diaphragm structure;

FIG. 3a is an enlarged view of the flanged edge of a pumping chamber showing one form of diaphragm securing structure;

FIG. 4 is a partial cross-sectional view, similar to but larger than FIG. 3, and showing a modification of the diaphragm sealing structure;

FIG. 4a is a partial sectional view showing a step of assembly of the device of FIG. 4;

FIG. 5 is a view similar to FIG. 4, showing another diaphragm sealing modification;

FIG. 6 is a view of a face of the modification of the diaphragm shown in FIG. 5;

FIG. 7 is a view similar to FIG. 6 showing another modification; and

FIG. 8 is a schematic diagram of a pump system.

Referring now to the drawings and particularly to FIGS. 1 and 2 thereof, a pump assembly 10 has as its principal elements a pair of pumping units 12 and 14 which are fixedly mounted on a base plate 16. The pumping units 12 and 14 are hydraulically connected to a control valve 18 by suit-able means, not shown in FIG. 1, for pumping a liquid such, for example, as paint from inlet ports 20 and 22, respectively, to outlet ports 24 and 26, respectively. As more fully described hereinafter in connection with FIG. 8, the control valve 18 is connected between the outlet of a hydraulic fluid pump connected to the inlet port 28 and a hydraulic fluid sump connected to the outlet port 30. A reinforcing support bar 31 is fastened at its ends to the units 12 and 14. The spool 32 of the control valve 18 is mechanically connected to the diaphragms in both of the pumping units 12 and 14 which are connected to operate in out-of-phase relationship. Hence, when the unit 12 is pumping fluid out of its pumping chamber, the other unit 14 is drawing fluid into its pumping chamber. At the end of each such stroke, the spool 32 is moved to its opposite position within the chamber of the control valve 18 thereby to reverse the operation of both of the pumping units 12 and 14. A more complete description of the operation of the pump 10 will be given hereinafter with reference to FIG. 8.

The pumping units 12 and 14 are identical in construction and, therefore, only the unit 12 will be described in detail. Therefore, referring to FIG. 3, it may be seen that the pumping unit 12 comprises a pair of dome-like forged pump sections 34 and 36 which have respective peripheral flanges 3 8 and 40 secured together by a plurality of spaced-apart bolts 42. A metal backing ring 43 and a thin walled flexible diaphragm 44 of generally circular shape are located between the castings 34 and 36. The ring 43 is preferably of soft strong metal such as annealed steel, for example. An annular peripheral area of the diaphragm 44 and the backing ring 43 are preferably very'tightly compressed together between flat faced shouldered, recessed flange surfaces 38a and 40a thereby to provide a tight seal between a pumping chamber 46 located on one side of the diaphragm 44 and a driving chamber 48 located on the opposite side of the diaphragm 44, as well as sealing for leakage out of these chambers to surrounding areas. As best shown in FIG. 3a, the mating faces of flanges 38 and 40 exterior of the bolts 42 abut each other at line 3 9 to thereby control the compression of the diaphragm 44 and the ring 43. The peripheral edge of the backing ring 43 also abuts the line 49. High pressure of the fluid in the driving chamber 48 thus forces a metal to metal seal between the ring 43 and shoulders of the recessed faces 38a and 40a.

The diaphragm 44 is fabricated from film or a very thin sheet of polyvinyl fluoride and is preferably, but not essentially, substantially circular in shape and has a hole in its center in the embodiment herein shown. It is to be noted that a single action pump operable from vacuum intake pressure to high driving pressure would not require such center hole. The diaphragm 44 can be flat before assembly, or it can be beat shaped as a flat lipped cup, substantially as shown in FIG. 3, for long-stroke pumps. Other embodiments of the diaphragm and the assembly thereof will be described below in connection with FIGS. 4 through 7.

The pump is supported by suitable means, not shown, on the base 16. The pump section 34 is provided with an axial aperture 52 in which a nipple 54 is secured to provide an inlet port to the pumping chamber 46. At the top of the pump section 34 a raised boss 56 is provided with a bore 58 in which a nipple 60 is secured to provide 'an outlet port. Each of the nipples 54 and 60 preferably includes a suitable valve seat and ball valve member spring biased to provide a pressure actuated check valve,

the nipple 54 permitting unidirectional flow of fluid into the chamber 46 and the nipple 60 permitting unidirectional flow of fluid out of the chamber 46. Separate check valves may be provided for this purpose if desired. In order to admit and emit hydraulic driving fluid to and from the drive chamber 48 to drive the diaphragm 44, the pump section 36 is provided with a bore 62 extending upwardly through a boss 64. A conventional high pressure nipple connector 66 is threadedly received therein.

In a preferred embodiment of the present invention, the diaphragms 44 in each of the pumping units 12 and 14 are mechanically connected together to insure that they reciprocate in exact correspondence and, moreover, to provide a common interconnecting member for controllab'ly positioning the spool 32 in the control valve 18. Accordingly, a tie rod 68, which is in the form of a solid cylinder, extends through a sealing member 70 which is in turn sealably secured in an axial hole 72 in the casting 36 and is connected to the center portion of the diaphragm 44. The diaphragm 44 is provided with a centrally disposed aperture 76 through which the end portion of the rod 6 8 extends. The end of the rod 68 is threaded and a nut 78 is secured thereto with a flat faced washer 80 positioned over the rod in abutment with the face of the nut 78. A similar flat faced washer 82 is positioned on the rod 68 on the opposite side of the diaphragm 44 and a nut 84 is threaded onto the end of the rod 68 to tightly compress the center portion of the diaphragm 44 between the members 80 and 82. In order to prevent wear on the .4 diaphragm as it flexes back and forth between the chambers 46 and 48, the faces of the washers and 82 are provided with rounded outer edges 86 at least on the diaphragm abutting side thereof. Consequently, there is no sharp edge about which the diaphragm 44 must flex as it moves back and forth within the unit 1 2 and the life of the diaphragm 44 is extremely long. As shown in the drawing the internal edges of faces 38a of the backing ring 43 are also rounded smoothly to permit free flexure of the diaphragm 44.

The rod 68 and a corresponding rod 88 in the pumping unit 14 are each threadedly connected to an arm 90 to which a pair of nuts 92 and 94 are secured. Accordingly, as the diaphragms 44 move back and forth in the pumping units 12 and 14, the arm 90 also moves back and forth from left to right, as viewed in FIG. 1.

To control the operation of the control valve 18 in accordance with the position of the arm 90, a control rod 96 is axially connected to the valve spool 32 and loosely extends through a. hole 98 in the arm 90. A pair of stop washers 100 and 102 are fixedly secured as by welding to spaced-apart positions on the rod 96 and a pair of coil springs 104 and 106 are positioned over the rod 96 between the arm 98 and the respective stops 100 and 102. As the rod 90 moves toward the left, as it is illustrated in FIG. 1, the spring 104 is progressively compressed to exert an increasing force toward the left, tending to move the spool from its right-hand position which it occupies in FIG. 1, and in which it is supplying pressurized hydraulic fluid to the unit 12, to its left-hand position, wherein it connects the drive chamber of the unit 12 to the sump and connects the pressurized fluid to the drive chamber of the unit 14.

The spool 32 is held in one or the other of its two extreme positions by means of a ball detent arrangement comprising a spherical member 108 which is pressed by means of a light coil spring 110 into one or the other of a pair of spaced-apart axial grooves 112 and 114 in a rod 116 extending axially to the right from the spool 32. The ball detent is adjusted by means of a machine screw 118 so that it exerts a sufficient holding influence on the spool 32 to maintain it in one or the other of its two stable positions until the diaphragms 44 have reached the point at which it is desired to reverse their strokes. At this time, one or the other of the springs 104 and 106 is sufficiently compressed so that the axial force exerted on the rod 96 overcomes the holding force of the detent assembly, thereby to push the ball 108 against the spring 110 into the associated bore to free the rod 116 for movement into the other position where the ball 108 is forced by the spring 110 into the other one of the grooves 112, 114.

In order to insure that the spool is not stopped at an intermediate position, it is desirable to use a ball 108 having a diameter substantially less than the diameter of the grooves 112 and 114. -In this way, a substantial holding force can be produced on the rod 116 without employing a very high spring pressure on the ball. Therefore, when the spring pressure is overcome and the ball 10 8 is moved against the spring 110, the frictional force exerted through the ball 108 on the portion of the rod 116 between the grooves 112 and 114 is extremely small and less than the force exerted on the rod 96 by the expanding spring 104, 106 which has previously been compressed.

The faces of flanges 38 and 40 securing the diaphragm 44 are preferably held to a flatness requiring close tolerances in machining. Such tolerances can be held for small domes, and for pumps operable at relatively low pressures and the soft metal ring 43, FIG. 3, can compensate for small irregularities and thus seal the pump against leakage. At higher pressures, however, the flanges 38 and 40 may yield, the securing bolts 42 may yield, and the diaphragm 44 could be blown out from between the flanges 38 and 40. To compensate for yielding of parts, and to reduce tolerance requirements, other sealing means including more yieldable sealing means are desirable and preferred for large pumps and/or very high pressure pumps.

FIG. 4 is an enlarged partial sectional view similar to FIG. 3. A flexible plastic or rubber-like backing ring 160 is compressed in the driving fluid side of a pump. The flange 40 is recessed by a shouldered V-groove 46b into which an annular steel hoop 161 fits and bridges the abutting faces of flanges 38 and 40. The groove face abuts the right side of the ring 160 and the left side thereof abuts the right side peripheral edge of the diaphragm 44. The left side of the diaphragm 44 abuts a facing shouldered V-groove 38b in the flange 38. The bolts 42 are drawn up tightly to secure the diaphragm 44 and the ring 160 sufficiently so that the ring 160 flows within its elastic limit to the cross-section shown.

Referring to FIG. 4a, a step of assembly of the sealing mechanism is shown. The ring 161 abuts the axially aligned inside edges 38c and 40c of V-grooves 38b and 40b. The peripheral edges of the diaphragm. 44 and the backing ring 160 are preferably of slightly less diameter (approximately one-sixteenth of an inch for a seven inch diameter diaphragm) and can rest in the position shown, but rotated clockwise or counterclockwise ninety degrees, to facilitate assembly. The bolts 42 are preferably drawn up progressively crisscross lightly until all require more than hand screw-driver torque; and thereafter with wrench torque until the mating faces of flanges 38 and 40 engage each other. Thereafter, if desired, and preferably for very high pressure service, the bolts may be strained to approximately one-third of their yield point stress. For either of the above stresses, the edge of the diaphragm 44 and the cross-section of the backing-ring 160 will take a configuration substantially as shown in FIG. 4. Due to tool marks and irregularities of shoulder metal in the grooves 38b and 40b air can bleed out past the metal hoop 161, and the ring 161 will be urged outwardly by flow of material at the outer edges of the diaphragm 44 and the backing-ring 160. It is to be noted that a diaphragm 44 backing flexing bead 16111 is also provided.

After compression of the backing ring 168- into the grooves 38b and 40b pressures can be retained up to pressure values at which the material of which the ring 160 is fabricated changes state or physical characteristics. As the flanges 38 and 40 move back and forth at extreme pressures, the driving and driven fluids may tend to oscillate toward and away from the grooves 38b and 4%. However, if the initial compression of the material of the ring 160 is sufliciently above such extreme pressure, no fluids will be permitted to gain access to the grooves. Even at higher pressures, with some fluid gaining such access, there will still be no fluid leakage because the frusto-conical area of the grooves (and the flexible parts 44 and 160 in contact therewith normally) is greater than the peripheral area of the flexible parts touching shoulder portions adjacent the sealing hoop 161 to inhibit external or cross-chamber leakage. It has been found that the sealing hoop 161 need not be endless, although such structure is preferred, but can be overlapped at its ends for a small percentage of its circumference, while still providing this desirable sealing feature.

A compressible washer 162 may be provided for backing the center of the diaphragm 44 to compensate for irregularities of the faces of the washers 80 and 82. Since there is only a very slight differential pressure across the diaphragm it is not necessary to compress the flexible washer 162 to the extent that the ring 160 is compressed. Both the washer 162 and the ring 160' have been satisfactorily fabricated from a suitable rubber and/or plastic as polyurethane, for example. Other suitable materials having similar physical and chemical characteristics for resisting attack by driving fluid could be used in the pump. The ring 160 and the washer 162 may be suitably sealed to the diaphragm 44 if desired to facilitate pump assembly; however, this step is not essential for practicing the invention.

FIG. 5 illustrates another modification of the invention; and is similar to the modification disclosed in FIG. 4. A backing diaphragm 164, preferably of polyurethane or Buna-N rubber, is shown as completely covering the driving pressure side of a diaphragm 44a and being compressed thereto by recesses 38b and 40b in the flanges 38 and 40 at the peripheries thereof; and between washers and 82 at the centers thereof. The annular hoop 161 also serves similar purposes herein as in FIGS. 4 and 4a. It is preferred that the diaphragms do not ad here to each other at their respective flexing areas to minimize localization of stress in the diaphragm 44a. To attain this desirable feature, the diaphragm 44a is preferable closely dimpled as indicated to reduce adherence to the diaphragm 164. The same can be made from pre-dimpled film and same will flatten out to form a tight pressure seal beneath the flange 38 and the washer 82.

The dimpling further can provide for atmospheric air pressure assembly of the two diaphragms by laying one upon the other and mechanically expressing air out therebetween. The reaction of the dimples will create a partial vacuum upon release of mechanical pressure. To readily attain such assembly, the diaphragm is peripherally and centrally flat, as shown in FIG. 6 at areas 166 and 168 to provide edge seals. For long-stroke diaphragms, it is preferred that annular concentric corrugations 4412, as illustrated in FIG. 7, be closely spaced and used in preference to dimples. The areas 166 and 168 can be smooth and flat if desired for sub-assembly, but such construction is not required.

As stated above, the diaphragms 44 and 44a are preferably substantially two-thousandths of an inch thick. The backing ring 160 and washer 162, and the backing diaphragm 164 may be several times this thickness, as desired. For example, and not in a restrictive sense, it has been found that backing members between thirty and sixty thousandths of an inch serve favorably. Obviously thinner and thicker backing members could be utilized in keeping with the invention. Both of the diaphragms can be cup-shaped, if desired, for long stroke pumps or the like.

OPERATION Referring to FIG. 8, there is illustrated a schematic diagram of the pumping system of which some of the parts are shown in greater detail in FIGS. l-3. The modifications disclosed in FIGS. 4, 5 and 6 will operate in the same manner. As shown, the control valve 18 has its port 30 connected via a conduit to the drive chamber of the pumping unit 12. In like manner, the port 28 is connected by means of a conduit 132 to the drive chamber of the pumping unit 14. A suitable high pressure pump 134 is connected between a hydraulic sump 136 and the inlet to the control valve 18. The return port of the control valve 18 is connected by means of a return conduit 138 to the sump 136. If desired, a controllable by-pass line 140 between the conduit 138 and the sump pump 134 may be provided to control the temperature of the hydraulic fluid which is; being pumped to the drive chambers in the units 12 and 14 thereby to control the temperature of the hydraulic fluid and hence that of the liquid being pumped by the system.

The control valve 18 and the remainder of the system are illustrated in FIG. 8 in the same condition as they are illustrated in FIGS. 1 through 3, and consequently the hydraulic fluid pumped by the pump 134 is being fed through the valve 18 and the conduit 130 to the drive chamber in the unit 12. Accordingly, the diaphragm 44 shown in FIG. 3 is being forced to the left, thereby to force the paint or other liquid contained in the pumping chamber therein out through a check valve 142 to a common outlet manifold 144. The check valve 146 connected between the pumping unit 12 and the paint or other liquid supply prevents the liquid from the pumping unit 12 from being returned to the supply. At this same time, the diaphragm 44 in the pumping unit 14 is being pulled to the left by means of the rods 68 and 83 thereby to force the hydraulic fluid in the pumping chamber thereof through the conduit 132, the valve 18 and the conduit 138 to the sump 136 or to the by-pass line 140 as the case may be. The paint or other liquid to be pumped is at this time being sucked through the check valve 148 from the supply source into the pump ing chamber. A check valve 150 connected between the pumping unit 14 and the common manifold 144 is closed at this time to prevent pulling paint from the manifold 144 back into the pumping unit 14.

With the valve 18 in this osition, the rods 68 and 38 are moving towards the left thereby compressing the spring 144 until such time as the force exerted on the control rod 96 becomes sufliciently great to overcome the holding force exerted by the ball detent arrangement thereon. When the holding force is overcome and the ball 108 is forced out of the groove 112 against the spring 110, the spool 32 moves to the left to its other stable position with a snap-action whereby the ball 108 is received in the groove 114. At this time the outlet of the pump 134 is connected through the valve 18 to the conduit 132 and the conduit 130 is connected through the valve 18 to the conduit 138 connecting to the sump 136 and/or the by-pass line 140. Accordingly, hydraulic pressure is exerted on the diaphragm 44 in the pumping unit 14- to force it to the right, thereby expelling the paint or other liquid through the check valve 150 into the common outlet manifold 144. When the coil spring 106 has been sufficientlycompressed to exert a force on the rod 96 which overcomes the holding force exerted by the ball detent arrangement thereon, the spool 32 is moved to the right until the ball 108 again seats in the groove 112.

Should the spool 32 become jammed in the intermediate position, both of the pumping chambers in the units 12 and 14 are partially connected to the return conduit 138 and no damage can be caused to the various parts of the unit.

The foregoing description has been directed to presently preferred structure including modifications of same for different purposes. Obviously other modifications and changes will occur to those skilled in the pump and related arts. Accordingly, it is desired that the invention be not restricted to the specific details shown and described; but be limited only by the scope of the following claims.

I claim:

1. A fluid pressure balancing device comprising a housing for containing fluid, means in the housing forming a cavity, a flexible polyvinyl fluoride fluid pressure balancing diaphragm being at least one-half of one-thousandth of an inch and less than thirty-one thousandths of an inch in thickness spanning a portion of the cavity to provide fluid chambers within the housing separated by the diaphragm, means for maintaining the position of the diaphragm in the cavity and for preventing fluid communication between the chambers, one of the chambers being provided with fluid inlet and fluid outlet means, and another of the chambers being provided with pressure responsive means for actuating the diaphragm to control fl-uid flow through the fluid inlet and outlet means of one of the chambers.

2. The fluid pressure balancing device of claim 1 wherein the housing comprises mating parts formed to provide a cavity therebetween when secured together and the means for maintaining the diaphragm position and for preventing fluid communication between the chambers provided thereby are mating surfaces of the mating housing parts.

3. A pressureabalanced diaphragm pump comprising a housing, means in the housing forming a cavity, a flexible polyvinyl fluoride fluid pressure balancing diaphragm being at least one-half of one-thousandth of an inch and less than thirty-one thousandths of an inch in thickness disposed across a portion of the cavity to provide driving fluid and driven fluid chambers in the housing separated by the diaphragm, means on the housing bordering the diaphragm for maintaining its position with respect to the housing and for preventing fluid communication between the chambers, inlet means establishing communication between a source of fluid supply and the driven fluid chamber, outlet means connected to the driven fluid chamber, and means for actuating the diaphragm through the driving fluid chamber to produce the pumping action of the diaphragm.

4. The pump of claim 3 wherein the diaphragm is cup-shaped.

5. The pump of claim 3 wherein the diaphragm has a generally cup-shaped central portion bordered by a substantially flat peripheral lip, the flat peripheral lip being engaged by the means on the housing bordering the diaghragm for maintaining its position and for preventing fluid communication between the chambers.

6. The pump of claim 3 wherein the diaphragm thickness is in the range of one-half of one-thousandth of an inch to thirty-one thousandths of an inch.

7. In a diaphragm pump having a housing, the housing being provided with a cavity, a diaphragm in the housing dividing the cavity into pressure chambers, one of the chambers having a pumped fluid inlet and outlet, another chamber having a pressure responsive means for actuating the pumping action of the diaphragm, the improvement wherein the housing has separable mating parts forming a cavity, the parts have surfaces mating along a plane, the mating parts are recessed inwardly of the mating surfaces to provide a generally continuous recess inwardly of the plane of the mating surfaces, the diaphragm for dividing the cavity is a thin flexible diaphragm having the peripheral edge thereof positioned in the recess provided by the mating parts, a resilient seal is disposed in the recess and has a surface thereof spanning the plane defined by the mating surfaces of the housing parts, one of the surfaces of the first seal engages one of the surfaces of the diaphragm in the recess, and a means is provided for establishing the engagement of the mating parts to urge a recess defining surface of one of the mating parts against the resilient first seal and a recess defining surface of the other of the mating parts against the diaphragm whereby the first seal .is made to span the plane defined by the engaging mating surfaces of the housing parts to prevent the extrusion of the thin diaphragm from between the mating surface of the housing while sealing the diaphragm in the recess between the mating parts and preventing fluid interchange between the chambers provided by the diaphragm.

8. The pump of claim 7 wherein a second seal is disposed in the recess provided by the mating parts and radially outwardly of the edge of the diaphragm and the first seal, the second seal spanning the plane defined by the mating housing surfaces and lying in a plane positioned generally normal to that of the mating parts.

9. The pump of claim 8 wherein the recess, the first seal and the second seal have generally annular configurations and the diaphragm is generally circular.

10. The pump of claim 7 wherein the recess provided by the mating housing parts is formed with a generally frusto-conical cross-sectional configuration with the crosssectional area of the recess decreasing in a radially inward direction.

11. The pump of claim 10' wherein a second seal is provided adjacent the radially outermost surface of the frusto-conical recess and in substantially surface to surface con-tact with the surfaces of the mating parts defining the base of the frusto-conical recess, the second seal spanning the plane defined by the mating housing surfaces, the diaphragm overlying one of the converging surfaces of the recess and the first seal overlying the other of the converging recess surfaces whereupon the establishment of the engagement of the mating housing surfaces produces the deformation of the resilient first seal both into and out of the recess whereby the diaphragm is forced firmly against a converging surface of the recess and the second seal is urged firmly against the base of the recess and pressures developed in the chamber communicating with the seal serve to enhance the sealing eflect on the diaphragm and second seal.

12. In a fluid pressure balancing device, a flexible polyvinyl fluoride pressure balancing diaphragm being at least one half of one-thousandth of an inch and less than thirtyone thousandths of an inch in thickness, and yieldable backing means for providing added thickness for said diaphragm adjacent at least one area provided for securement of same to another part of said device.

13. The device of claim 12, said backing means comprising a second plastic diaphragm substantially equal in area and configuration to said polyvinyl fluoride diaphragm.

14. The device of claim 13, and mechanical means for securing said diaphra'gms together.

15. The device of claim 12, said backing means being polyurethane and substantially thicker than said polyvinyl fluoride diaphragm.

16. The device of claim 13, said second diaphragm being vinyl and substantially thicker than said polyvinyl fluoride diaphragm.

17. In a fluid driven balanced pressure pump, pump means comprising in combination, housing means forming a cavity, a polyvinyl fluoride flexible fluid pressure balancing diaphragm dividing said cavity into driving fluid and driven fluid chambers, and means securing said diaphragm to said cavity forming means, said diaphragm being more than one-half of one-thousandth of an inch and less than thirty-one thousandths of an inch in thickness.

18. In a fluid pressure balancing device, a flexible polyvinyl fluoride pressure balancing diaphragm, said diaphragm being at least one-half of one-thousandth of an inch and less than thirty-one thousandths of an inch in thickness; yieldable backing means for providing added thickness for said diaphragm adjacent at least one area provided for securement of same to another part of said device, said backing means comprising a second plastic diaphragm substantially equal in area and configuration to said polyvinyl fluoride diaphragm, and mechanical v10 means .for securing said diaphragm together, said polyvinyl fluoride diaphragm being wrinkled before assembly with said second diaphragm to reduce adherence therewith.

119. In a fluid pressure balancing device, a flexible polyvinyl fluoride pressure balancing diaphragm, said diaphragm being at least one-half of one-thousandth of an inch and less than thirty-one thousandths of an inch in thickness, and yieldable backing means for providing added thickness for said diaphragm adjacent at least one area provided for securement of same to another part of said device, said backing means being polyurethane and substantially thicker than said polyvinyl fluoride diaphragm, said polyvinyl fluoride diaphragm being wrinkled before assembly with said backing means to reduce adherence therebetween.

20. A flexible polyvinyl fluoride fluid pressure balancing diaphragm, said diaphragm being at least substantially one-half of one-thousandth of an inch and less than substantially thirty-one thousandths of an inch in thickness, said diaphragm being wrinkled prior to use thereof.

21. A flexible polyvinyl fluoride fluid pressure balancing diaphragm, said diaphragm being at least substantially one-half of one-thousandth of an inch and less than substantially thirty-one thousandths of an inch in thickness, said diaphragm being wrinkled prior to use, a relatively thicker plastic backing diaphragm, and means for mechanically securing said diaphragms together.

References Cited by the Examiner UNITED STATES PATENTS 326,545 9/1885 Class et al 230- X 491,116 2/1893 Keeney 103--152 2,175,460 10/1939 Guildford 92102 X 2,419,010 4/ 1947 Coffman et al. 260-921 X 2,645,062 7/1953 Senesky 92-102 X 3,081,208 3/1963 Bottorf et al. 260-921 3,104,617 9/1963 Barr 103150 3,207,080 9/;l965 Schlosser 103--152 MARK NEWMAN, Primary Examiner.

WARREN E. COLEMAN, Examiner. 

1. A FLUID BALANCING DEVICE COMPRISING A HOUSING FOR CONTAINING FLUID, MEANS IN THE HOUSING FORMING A CAVITY, FLEXIBLE POLYVINYL FLUORIDE FLUID PRESSURE BALANCING DIAPHRAGM BEING AT LEAST ONE HALF OF ONE-THOUSANDTH OF AN INCH AND LESS THAN THIRTY-ONE THOUSANDTHS OF AN INCH IN THICKNESS SPANNING A PORTION OF THE CAVITY TO PROVIDE FLUID CHAMBERS WITHIN THE HOUSING SEPARATED BY THE DIAPHRAGM, MEANS FOR MAINTAINING THE POSITION OF THE DIAPHRAGM IN THE CAVITY AND FOR PREVENTING FLUID COMMUNICATION BETWEEN THE CHAMBERS, ONE OF THE CHAMBERS BEING PROVIDED WITH FLUID INLET AND FLUID OUTLET MEANS, AND ANOTHER OF THE CHAMBERS BEING PROVIDED WITH PRESSURE RESPONSIVE MEANS FOR ACTUATING THE DIAPHRAGM TO CONTROL FLUID FLOW THROUGH THE FLUID INLET AND OUTLET MEANS OF ONE OF THE CHAMBERS. 